1. Field of the Invention
The present invention relates to a two-axis angular rate gyroscopic apparatus in general and in particular to a two-axis angular rate gyroscope having a flexible rotatable disk. The rotatable disk comprises a central hub portion and a plurality of movable perforated members, each of which extend from said hub portion for providing increased performance at low disk speeds.
2. Description of the Prior Art
A two-axis angular rate gyroscopic apparatus comprises a rotatable disk. The disk is rotated by a motor or the like. As the disk is rotated, it is rotated past a stationary sensing mechanism. The sensing mechanism and the disk may comprise a magnetic head assembly, a capacitor assembly, an optical assembly, or the like.
In operation, the rotating disk will tend to undergo precession when the axis of rotation of the disk is rotated about an axis perpendicular to the axis of rotation. If the disk is flexible, the gyroscopic action will cause the disk to flex. The amount of flexure is detected by the sensing mechanism for generating a signal corresponding thereto.
Heretofore, an angular rate gyroscope using a rotating disk has had a disk of uniform thickness requiring that it be rotated at a relatively high speed, e.g. 20,000 rpm, in order to obtain a measurable precession for low angular rate changes. In general, gyroscopes which operate at high rpms are difficult and expensive to manufacture and typically produce a loud and sometimes annoying high-pitched sound. Such a sound and expense is undesirable in many applications, particularly those comprising consumer products involving closely associated human activities. For example, in a vehicular navigation system wherein an angular rate gyroscope is used for sensing the turning and pitching of an automobile, the expense could be prohibitive and the sound would be extremely annoying.